Ubuntu 15.10 64big Geforce 970M
Broken: Blender 2.76b official
When using a scale node for an image the plane track deform node will still use the original image bounds for the plane track deform, thus for example scaling the image further down.
The bug appears to happen in the scale node. It does scale the image, but does not change the image bounds, even when set to absolute.
Exact steps for others to reproduce the error
In the attached file, when the top of the 3 image nodes is plugged into the upper scale node, you see the effect. The middle image is exactly 275 x 275 and thus not effected.